Hi,
I've had the same issue (at least it looks very similar) as described above.
I have an ADSL 512k (both up and down, that seems to be the way in China) connection, with a ZTE ZXDSL831 routing modem, with NAT enabled (I know it works, I usually get high ID, and the connection used to work fine, and now works well for limited time).
Whenever I'm using amule (or shareaza, or emule, I've tried those ones as well) my internet connection seems to be cut at random intervals.
When this happens, I can't even ping my router, basically nothing goes out.
I've tried the conservative settings above (DL=28k, UL=7k, slot=4, max new connections/5 secs=5, max connections=25, max sources/file=150), but that doesn't change much.
It does not seem to be linked with DL speed, as ftp/http DLs work very well (often over 60kB/s).
Could this be linked to the NAT table being saturated ?
Thanks for any advice !
Laurent